What I did on my 7 horns was to first clamp each elevator in place centered on the HS. I just used some scrap plywood to protect the skins and lightly clamped the HS and the elevator together. Then I installed the bushing and drilled into the elevator horn. I got the bushing from McMaster-Carr. They are a little hard to find on the website, but they have them so keep looking. The bushing fit is too tight so I chucked it up in my drill press and sanded it down ever so slightly. I saw this on VAF somewhere I think. Worked like a charm. You can only drill one elevator at a time. Once they are both drilled I mounted them and installed the bolt as a test. Worked great. Don't be too worried if the horns don't align. Mine don't exactly and this seems to be common from my reading on this site.
This is just how I did it and you can do it however it works best for you.
